1. Field of the Invention
The present invention relates to a magnetic element which outputs a signal depending on the magnetic arrangement of two magnetic electrodes, and a magnetic signal processing device using the magnetic element.
2. Description of the Related Art
In the conventional electronics, the degree of freedom of “charges” is used as the degree of freedom of electrons. Recently, however, a field called spin electronics is rapidly rising, which positively uses “spin”, i.e., another degree of freedom of electrons. When the degree of freedom of spin is used, a single element can have multiple functions. As a result, various kinds of devices are expected to become compact, and an energy saving effect is expected to be obtained. In addition, the nonvolatility of spin also contributes to energy saving.
Various kinds of spin transistors such as a spin MOSFET, spin SET, and spin resonance transistor have conventionally been designed by adding the degree of freedom of spin by changing the electrode portion of a MOSFET, single-electron transistor (SET), or resonance tunneling transistor to a magnetic material (e.g., S. Sugawara and M. Tanaka, Appl. Phys. Lett. 84, 2307 (2004), T. Matsuno, S. Sugawara, and M. Tanaka, Jpn. J. APPL. Phys. (2004)). Additionally, signal processing devices using the MR effect (TMR) between magnetic electrodes placed on and under a tunnel barrier have been proposed (e.g., A. Ney, et al., Nature, 425 (2003) 485, Jpn. Pat. Appln. KOKAI No. 2004-006775). These devices are fundamentally based on the spin dependent conduction phenomenon between two magnetic electrodes.
In these spin devices, how to control magnetization of the magnetic material serving as the electrode is of extreme importance in driving the devices. However, only a few devices are designed in consideration of magnetization control. The mainstream method controls magnetization of a magnetic material by a magnetic field, as is proposed by A. Ney, et al. However, in the magnetization control method using a magnetic field, since a nanolevel magnetic material is hard to select because of the nature of the magnetic field, crosstalk readily occurs. Also, the smaller the size becomes, the higher the required power is. Hence, size reduction of the element and power saving are expected to be difficult. To solve this problem, Jpn. Pat. Appln. KOKAI No. 2004-006775 discloses a device using switching by spin-injection magnetization reversal. However, in the technique of Jpn. Pat. Appln. KOKAI No. 2004-006775, it is difficult to operate signals of magnetization reversal and signal processing independently. Hence, devices are hard to integrate.